1. Technical Field of the Invention
The present invention relates to a connector mounted on a printed circuit board. More particularly, the present invention is directed to a connector having an improved structure for preventing the connector from cracking when attached to a printed board.
2. Background of the Related Art
A conventional connector mounted on a printed circuit board is shown in FIGS. 4-6. A bottom face 1a of a connector housing 1 is a mounting face which is mounted on a printed circuit board 2. Screw holes 4 which receive screws 8 are formed on the bottom face 1a, so that the bottom face la and the printed circuit board 2 are connected by the screws. Moreover, a connection area 3 for engaging with a mating connector is formed on a top face of the connector housing 1.
A plurality of terminals 5 are provided on the connector housing 1. Top portions 5a of the terminals 5 are projected to the connection area 3 of the connector housing 1, and bottom portions 5b of the terminals 5 are protruded from the bottom face 1a of the connector housing 1. The top portions 5a projecting to the connection area 3 are connected with terminals of the mating connector (not shown), and the bottom portions 5b protruding from the bottom face 1a are connected with the printed circuit board 2 as shown in FIG. 6. In FIG. 6, solders 9 achieve this connection.
To determine the position of the connector housing 1 with regard to the printed circuit board 2, a guide rib 6 is provided on the bottom face 1a of the connector housing 1. The guide rib 6 has a narrow stick-like shape and protrudes from one end portion of the connector housing 1 as shown in FIG. 4. As shown in FIG. 6, the position of the connector housing 1 is determined by inserting the guide rib 6 into insertion hole 7 formed on the printed circuit board 2. Furthermore, the guide rib 6 prevents irregular rotational movement of the connector housing 1 while it is being fixed to the printed circuit board 2 by use of the screws 8.
In such a conventional connector, when the screws 8 are tightened to fix the connector housing 1 to the printed circuit board 2, the tightening stress concentrates to an edge portion 10 which is around the guide rib 6 piercing the printed circuit board 2. Thus, a crack 11 occurs on a base portion of the guide rib 6 as shown in FIG. 7, and finally the guide rib 6 may break. Hence, the reliability of the mounting connector housing 1 to the printed circuit board 2 is compromised.
FIG. 8 shows an improved connector with tapered portions 12 formed around the base portion of the guide rib 6 to prevent the crack 11 from occurring on the base portion of the guide rib 6. The tapered portions 12 are formed such that the diameter of the arc gets larger than the base portion of the guide rib 6, toward the bottom face 1a of the connector housing 1. This causes the tightening stress of the screws 8 to be dispersed, so that the concentration of the tightening stress is reduced, and thus the crack on the base portion of the guide rib 6 can be avoided.
When such tapered portions 12 are formed, however, a gap d between the connector housing 1 and the printed circuit board 2 appears because the tapered portions 12 contact with the printed circuit board 2, and thus the connector housing 1 cannot adhere to the printed circuit board 2. This causes unstableness of the connector housing 1. As a result of the unstableness, other problems of the mounting can occur, such as the solders 9 being exfoliated.
The present invention has been made in view of the above problems, and an object of the invention is to provide a connector having a structure which prevents the cracking on the base portion of the guide rib caused by the tightening of the screws, and can be mounted stably on the printed circuit board.
The above object has been achieved with a connector of the present invention of claim 1 having a connector housing; terminals provided on a bottom face of the connector housing and connected to a printed circuit board; a guide rib protruded from the bottom face of the connector housing; and a hollowed groove portion formed around a base portion of the guide rib on the bottom face of the connector housing, wherein the position of the connector housing with regard to the printed circuit board is determined by the guide rib.
The groove portion surrounding the base portion of the guide rib disperses the stress that occurs when the connector housing is fixed on the printed circuit board. Since the stress does not concentrate to the base portion of the guide rib, the cracking on the base portion of the guide rib can be avoided.
Since the groove portion is formed in a hollow manner, this portion does not contact with the printed circuit board and is not an obstacle to the mounting of the connector housing. Thus, the connector housing can be attached on the printed circuit board stably.
Another aspect of the present invention provides screw holes for fixing the connector housing to the printed circuit board on the bottom face of the connector housing, and provides the guide rib near one of the screw holes.
By providing the screw hole near the guide rib, a tightening force of the screw directly effects the guide rib, so that the guide rib can be fixed firmly to the printed circuit board. Also, the groove portion is formed on the base portion of the guide rib so that the screw tightening stress can be dispersed, thus the cracking on the base portion of the guide rib is avoided.
Another aspect of the present invention provides a guide hole for piercing the guide rib on the printed circuit board. By piercing the guide rib through the guide hole, the positioning of the connector housing to the printed circuit board can be achieved securely.